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    <title>Document</title>
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    <script>
        var number = prompt('请输入一个数字');
        var flag=true;
        for (var i = 2; i < number; i++) {
            if (number % i == 0 ) {
                flag=false;
                alert(+number + '不是一个质数');
                break;
            }
        }
        if(flag){
            alert(+number + '是一个质数');
    }
            

    </script>
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